A novel green phosphor for three band white LEDs

Sivakumar Vaidyanathan; Varadaraju Upadhyayula

doi:10.1117/12.614299

14 September 2005 A novel green phosphor for three band white LEDs

Sivakumar Vaidyanathan, Varadaraju Upadhyayula

Proceedings Volume 5941, Fifth International Conference on Solid State Lighting; 594110 (2005) https://doi.org/10.1117/12.614299
Event: Optics and Photonics 2005, 2005, San Diego, California, United States

Abstract

Current technology of lighting is Solid state lighting using LED's (SSL-LED). The aim of the present study is to find the critical concentration of Eu²⁺ for high emission intensity and also the role of Ce³⁺ co-doping on the absorption and emission properties in the host BaMgSiO₄. Photoluminescence emission of Eu²⁺ in BaMgSiO₄ when excited with 370 nm shows a broad band in the region 450 to 550 nm with a maximum at 502 nm and a shoulder at ~480 nm and one more band at ~ 400nm. The three emissions are due to Eu²⁺ in three different Ba sites in the lattice. Studies on Ba_{1 x}Eu_xMgSiO₄ [x = 0.0025 - 0.1 in steps of 0.0025] show that the emission intensity is maximum for x = 0.075 and a decrease in emission intensity is observed for higher x values. Ce³⁺ luminescence is studied for the first time in BaMgSiO₄. Ce³+ emission occurs as a broad band with maximum at 430 nm when excited with 356 nm. The Eu²⁺ excitation that occurs in the region 250 - 420 nm covers both the Ce³⁺ absorption and emission. Hence Ce³⁺ to Eu²⁺ energy transfer is possible in BaMgSiO₄. In the case of Ba_{0.99 x}Eu_0.01Ce_xMgSiO₄ [ x = 0.0025 - 0.1 ], it is observed that the emission intensity of Eu²⁺ increases with increasing Ce³⁺ content up to 0.01. This result proves the energy transfer from Ce³⁺ to Eu²⁺. Thus, the co-doping of Ce³⁺ also enhances the absorption of Eu²⁺ in the near UV to blue region where the LED emission occurs. BaMgSiO₄:Eu²⁺, Ce³⁺ with bright green emission can find potential application as a green phosphor for SSL-LED technology.

Citation Download Citation

Sivakumar Vaidyanathan and Varadaraju Upadhyayula "A novel green phosphor for three band white LEDs", Proc. SPIE 5941, Fifth International Conference on Solid State Lighting, 594110 (14 September 2005); https://doi.org/10.1117/12.614299

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